The primary objective of this study is to characterize the cell cycle effect of new anticancer drugs used singly or in combinations. Approximately 20 new drugs or drug combinations, to be chosen in consultation with Division of Cancer Treatment, N.C.I., will be studied each year by both flow cytometry and autoradiography. A second objective is to provide information on the mechanism of action of the drugs, based on their effect on cell cycle kinetics and possible effects on nuclear chromatin conformation studied in situ by new developed flow cytometry techniques. The effect of each drug (or drug combination) will be studied over an appropriate range of concentrations and time intervals on 4 different cell types: SK-L7 human leukemia cells; Friend murine leukemia cells; normal human peripheral blood lymphocytes; and Ehrlich HD33 Tumor. Thus the drug effects can be compared on leukemic cells and normal lymphocytes, and on hemopoietic vs. non-hemopoietic cells.